Abstract—

The plasma coagulation factor XIII (рFXIII) is a key protein of the blood coagulation systems, the main function of which consists of the enzymatic covalent stabilization of the polymeric structure of fibrin. The protein has a heterotetrameric structure consisting of two catalytic (FXIII-A₂) and two regulatory (FXIII-В₂) subunits. Using a high resolution mass spectrometry, hypochlorite-induced oxidation of рFXIII molecules and its enzymatic form (FXIIIa) is studied for the first time. It is demonstrated that sulfur and aromatic amino acid residues are the most vulnerable residues to oxidative attack. The mass spectrometry data indicate that oxidized amino acid residues are found in all structural elements of the FXIII-A catalytic subunit in the protein we are studying (except for the activation peptide), while a number of domains remain in native form in the FXIII-В regulatory subunit. When treated FXIIIa with hypochlorite, additional modification sites both in the FXIII-\({\text{A}}_{{\text{2}}}^{*}\) and in the FXIII-В₂ subunits are detected. The data obtained allowed us to postulate that in the process of converting the proenzyme into FXIIIa, new amino acid residues (previously inaccessible to oxidizers) migrate to the surface of the protein globule and become vulnerable targets for oxidizer molecules, while some of the initially surface-exposed amino acid residues move inside the protein, losing their ability to participate in the oxidative modifications. Electrophoresis of reduced samples of covalently cross-linked fibrin detected a decrease in transglutaminase activity of oxidized FXIIIa manifested in the inhibition of the reaction of the formation of γ–γ-dimers. The ability of the рFXIII molecule to resist the oxidative attack due to its antioxidant structural adaptation to the effect of reactive oxygen species is discussed.

中文翻译：

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凝血因子XIII的氧化修饰：结构和功能方面

摘要-

血浆凝血因子XIII（рFXIII）是血液凝固系统的关键蛋白，其主要功能包括血纤蛋白聚合结构的酶促共价稳定作用。该蛋白具有由两个催化（FXIII-A的的异四聚结构₂）和两个调节（FXIII-В ₂）的子单元。使用高分辨率质谱，首次研究了次氯酸盐诱导的рFXIII分子及其酶形式（FXIIIa）的氧化。结果表明，硫和芳香族氨基酸残基是最容易受到氧化攻击的残基。质谱数据表明，在我们正在研究的蛋白质的FXIII-A催化亚基的所有结构元素中都发现了氧化的氨基酸残基（活化肽除外），而在FXIII-调节亚单位。当使用次氯酸盐，额外的修饰位点既在FXIII-处理FXIIIA \（{\文本{A}} _ {{\文本{2}}} ^ {*} \），并在FXIII-В ₂亚基被检测到。所获得的数据使我们可以推测，在将酶原转化为FXIIIa的过程中，新的氨基酸残基（以前是氧化剂难以接近的）迁移到蛋白质小球的表面，并成为氧化剂分子的易受攻击目标，而一些初始表面暴露的氨基酸残基在蛋白质内部移动，从而丧失了其参与氧化修饰的能力。对共价交联的纤维蛋白还原样品的电泳检测到氧化的FXIIIa的转谷氨酰胺酶活性降低，这在抑制γ-γ-二聚体形成的反应中表现出来。讨论了FX3分子因其抗氧化剂结构适应活性氧的作用而抵抗氧化攻击的能力。